The invention relates to a device for supplying electrical power to a fuel pump of a motor vehicle internal combustion engine, having a first terminal to be connected to a DC voltage source, and having a second terminal to be connected to the fuel pump.
Such devices connect the fuel pump to the DC voltage source when the internal combustion engine is started. The DC voltage source in today's motor vehicles is a battery, which is charged while the internal combustion engine is running. In this case, the fuel pump is designed for the voltage from the DC voltage source of 12 Volts, for example, and supplies the internal combustion engine with fuel. After starting, the fuel pump is normally supplied with a substantially constant voltage via an alternator driven by the internal combustion engine. The voltage from the DC voltage source, however, depends on the temperature, its age, service condition and other factors. In particular at low temperatures, the voltage from the DC voltage source drops severely, for example to 7 Volts. Thus at low temperatures, a reliable supply of fuel to the internal combustion engine is no longer guaranteed. In order to satisfy exhaust standards, today's engine management systems require defined pressures and delivery rates from the fuel pump as soon as the internal combustion engine is started.
One could have the idea to provide a plurality of fuel pumps designed for different voltages, and to drive a fuel pump designed for 7 Volts when there is a voltage of 7 Volts from the DC voltage source. At a voltage of 12 Volts, the system then switches to an internal combustion engine designed for 12 Volts. This, however, requires a very complex design and is thus extremely costly.